Voltage sags due to induction motor starting

Voltage sags due to induction motor starting:

1. Voltage sags can causes:

^ü   Motor load to start/ stop

^ü   Digital devices to reset causing loss of data

^ü   Equipment damage and /or failure

^ü   Materials spoilage

^ü   Lost production due to downtime

^ü   Additional costs

^ü   Product reworks

^ü   Product quality impacts

^ü   Cost of investigations into problem

^ü   Impacts on customer relations such as late delivery.

^ü   Lost of sales

2. Voltage sags due to Motor Starting:

^ü   Voltage sag produced by induction motor starting current is one of the main causes of sensitive equipment dropout.

^ü   The use of motor starter reduces the voltage sag depth but increases its duration.

^ü   The subsequent connection to full voltage originates new sag separated from the first one by a few seconds.

^ü   An induction motor will draw six to ten times its full load current while starting.

^ü   This lagging current then causes a voltage drop across the impedance of the system.

^ü   Generally induction motors are balanced 3 phase loads, voltage sags due to their starting are symmetrical.

^ü   Each phase draws approximately the same in rush current. The magnitude of voltage sag depends on,

^ü   Characteristics of the induction motor

^ü   Strength of the system at the point where motor is connected.